Precision Measurements of Nuclear γ-Ray Wavelengths of Ir192, Ta182, RaTh, Rn, W187, Cs137, Au198, and Annihilation Radiation

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Abstract
The sensitivity of the curved crystal gamma-ray spectrometer has been improved (1) by replacing the multicellular Geiger counter formerly used as a detector with a sodium iodide crystal scintillation counter and (2) by doubling the thickness of the quartz crystal which is used for diffraction of gamma-rays. Certain minute nonlinearities in the spectrometer have been detected and corrected in a recent calibration. An analysis of the precision of the instrument based on this calibration and a systematic treatment of errors due to random variations in counting rate is presented. Verification of the quoted precision is achieved by comparisons of wavelengths measured in various orders and by consistency of Ritz combinations.